Virus en mi web??

Esta mañana me ha llegado este email de wordfence:
Critical Problems:

* WordPress core file modified: index.php
* WordPress core file modified: wp-comments-post.php
* WordPress core file modified: wp-includes/ID3/module.audio-video.riff.php
* WordPress core file modified: wp-includes/SimplePie/Cache.php
* WordPress core file modified: wp-includes/SimplePie/Enclosure.php
* WordPress core file modified: wp-includes/category.php
* WordPress core file modified: wp-includes/class-wp-customize-setting.php
* WordPress core file modified: wp-includes/link-template.php
* WordPress core file modified: wp-includes/meta.php
* WordPress core file modified: wp-includes/plugin.php
* WordPress core file modified: wp-includes/shortcodes.php
* WordPress core file modified: wp-includes/theme-compat/comments.php
* WordPress core file modified: wp-includes/wp-db.php
* File appears to be malicious: index.php
Es un virus ???? o hackeada???